[1] Singapore Gen Hosp, Dept Gastroenterol & Hepatol, Singapore, Singapore
[2] Duke NUS Med Sch, Singapore, Singapore
[3] Huazhong Univ Sci & Technol, Tongji Med Coll, Dept Epidemiol & Biostat, Minist Educ Key Lab Environm & Hlth, Wuhan, Peoples R China
[4] Huazhong Univ Sci & Technol, Tongji Med Coll, Sch Publ Hlth, State Key Lab Environm Hlth Incubation, Wuhan, Peoples R China
[5] Univ Pittsburgh, Inst Canc, Div Canc Control & Populat Sci, Pittsburgh, PA USA
[6] Univ Pittsburgh, Grad Sch Publ Hlth, Dept Epidemiol, Pittsburgh, PA USA
[7] Natl Univ Singapore, Saw Swee Hock Sch Publ Hlth, Singapore, Singapore